The present invention relates to a circuit breaker, and particularly relates to a circuit breaker having an ablative arc quenching arrangement.
Circuit breakers are used in a wide variety of applications for controlling the flow of electrical current to an electrical circuit when an undesired electrical condition is detected. Circuit breakers typically include three major subassemblies: an operating mechanism, a trip unit and an interrupter. The trip unit and operating mechanism cooperate to activate the interrupter when the undesired condition is detected.
The interrupter typically has a movable contact arm that carries a movable contact. A stationary contact is arranged to be in contact with the movable contact when the contact arm is in the closed position. An assembly commonly referred to as an arc chute is positioned adjacent the path of the movable contact. The arc chute is comprised of a plurality of thin steel plates that are spaced apart along the path of the movable contact. Typically, the plates will have a portion removed allowing the movable contact to move within a slot created in the arc chute by the removed portion. Due to the performance requirements of the arc chute, many plates are typically required to be assembled into thermoset side plates, a costly and time consuming process.
When an abnormal operating condition is detected, the interrupter is activated causing the movable contact to separate and move away from the stationary contact. During this separation process, a plasma arc is formed between the contacts and electrical current continues to flow through the circuit breaker until the arc is extinguished. Generally, circuit breakers are designed to transfer the plasma arc into the arc chute as the contacts separate. The arc chute absorbs the energy, stretches the arc and increases the arc resistance causing the arc to eventually be extinguished. However, during this process vaporized metal is generated and exhausted from the circuit breaker along with hot gases from the plasma arc.
Accordingly, while present circuit breaker systems are suitable for their intended purposes, there is a need in the art for a circuit breaker arc quenching arrangement that improves performance and reduces manufacturing costs.